With the development of communication technology, a mobile communication system has developed to a system of system architecture evolution (SAE).
FIG. 1 is a schematic diagram illustrating a structure of an SAE system according to the related art.
Referring to FIG. 1, the SAE system includes an evolved universal terrestrial radio access network (E-UTRAN) 101 and at least includes a mobility management entity (MME) 105 and a core network of a user plane entity (i.e., a serving-gateway (S-GW)) 106. The E-UTRAN 101 is used to connect a user equipment (UE) to the core network. Moreover, the E-UTRAN 101 also includes more than one macro base stations (i.e., an evolved node B (eNB)) 102 and home base stations (i.e., a home eNB (HeNB)) 103, optionally includes a home base station gateway (HeNB GW) 104, the MME 105 and S-GW 106, which may be integrated into one module for implementation, or may be separated to be implemented individually. Herein, inter-connection between eNBs 102 is through an X2 interface. The eNB 102 is connected respectively to MME 105 and S-GW 106 through an S1 interface. Alternatively, the eNB 102 is connected to the optional HeNB GW 104 through the S1 interface, the HeNB GW 104 is connected respectively to the MME 105 and the S-GW 106 through the S1 interface.
In an early state of establishing the SAE system or during a process of operating the SAE system, much manpower and material resources are taken to configure and optimize parameters of the SAE system, especially to configure wireless parameters, so as to ensure good coverage and capacity of the SAE system, mobility robustness, load balancing when moving and speed of accessing user device, and the like. In order to save the manpower and material resources for configuration during SAE system operation, a method for self-optimizing the SAE system is currently proposed. During a self-optimization operation, eNB configuration or HeNB configuration is optimized actually according to a current state of the SAE system. The eNB and HeNB are referred as to eNB hereinafter to instruct the method for self-optimizing the SAE system.
FIG. 2 is schematic diagram illustrating a basic principle of self-optimizing an SAE system according to the related art.
Referring to FIG. 2, after the eNB powers up or accesses SAE, the self-optimization configuration may be performed. The operation includes eNB basic configuration and initial wireless parameter configuration. Herein the eNB basic configuration includes configuration of an internet protocol (IP) protocol address of the eNB, operation administration and maintenance (OA&M), authentication between the eNB and the core network. When the eNB is the HeNB, it is needed to detect the HeNB GW to which the HeNB belongs. Software and operation parameters of the eNB are downloaded to perform self-configuration. Initial wireless parameter configuration is implemented according to experience or simulation. Performance of each eNB in the SAE system may be impacted by environment of region where the eNB locates. Thus, the eNB needs to perform initial configuration of a list of neighbor cells and initial configuration of the load balancing specifically according to initial wireless parameter configuration of the environment of the region where the eNB locates. After the self-configuration operation is completed, many parameters configured for the eNB are not optimized.
In order to make the performance of the SAE system better, configuration of the eNB is needed to be optimized or adjusted, which is also called self-optimization of the mobile communication system. When the configuration of the eNB is to be optimized or adjust, the eNB may be controlled by the OA&M in a background to execute it. A standard interface may exist between the OA&M and the eNB. The OA&M transmits the parameters to be optimized to the eNB (which may be the eNB or the HeNB) through the interface.
Thereafter, the eNB optimizes the parameters configured to the eNB itself according to the parameters to be optimized. The operation may be executed by the eNB itself. For example, the eNB performs detection to obtain the performance to be optimized, performs optimization and adjustment to corresponding parameters of the eNB itself. Optimization or adjustment of eNB configuration may include self-optimization of the list of neighbor cells, self-optimization of the coverage and the capacity, self-optimization of mobility robustness, self-optimization of the load balancing, self-optimization of parameters of a random access channel (RACH), and the like.
Hereinafter, a basic principle of the self-optimization of the mobile robustness in Release 10 is described. When a radio link failure (RLF) or a handover failure occurs for the UE and the UE returns to a connection mode, the UE indicates that the UE has an available RLF report to the network. The network transmits a message to the UE to request the RLF report. The RLF report transmitted by the UE includes information of an e-UTRAN cell global identifier (ECGI) of a cell serving the UE lastly, an ECGI of a cell to which re-establishment is tried, an ECGI of a cell where a handover operation is, triggered lastly, time from handover triggered lastly to a connection failure, whether a reason of the connection failure is a RLF or handover failure, radio measurement. A base station obtaining the RLF report of the UE forwards the RLF report obtained from the UE to a base station of the cell serving the UE lastly. The base station of the cell serving the UE lastly determines whether the reason is too early handover, too late handover, handover to an error cell or a coverage hole. If the reason is the too early handover or the handover to an error cell, the base station transmits information of the too early handover or the handover to an error cell to the base station which triggers the too early handover or the base station where the UE is handed over to an error cell.
Therefore, a need exists for a method for supporting indication of a failure event to a source access system to avoid impact for a UE, reduce operator configuration, transmit a handover report to the source access system correctly, and improve performance of a mobile communication system.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.